1. Field of the Invention
This invention relates to a television receiver having a wide display with an aspect ratio of, for example, 16:9. This invention also relates to a frame-size adjusting apparatus. This invention further relates to a method of detecting aspect-ratio information in a television signal or a video signal.
2. Description of the Prior Art
The aspect ratio is defined as the ratio of frame width to frame height in television. Typical formats of source television signals are of a normal-aspect type and a wide-aspect type adapted to an aspect ratio of 4:3 and an aspect ratio of 16:9 respectively. In addition, there are various kinds of formats of normal-aspect source television signals.
A vista source television signal adapted to an aspect ratio of 4:3 represents a picture composed of a central effective region and two noneffective mask regions extending above and below the central effective region respectively. The central effective region, corresponds to an aspect ratio of 16:9. Generally, the noneffective mask regions are colored black.
Wide television receivers have display screens corresponding to an aspect ratio of 16:9. Some of the wide television receivers include aspect converting circuits designed for a vista source television signal. The aspect converting circuit processes a vista source television signal or controls a vertical deflection width (a vertical raster amplitude), and thereby enables the central effective region of a picture to fully occupy a display screen while excluding the upper and lower noneffective mask regions of the picture from the display screen.
In general, wide television receivers can visualize normal-aspect source television signals as well as wide-aspect source television signals. Some of the wide television receivers are able to visualize normal-aspect source television signals of various formats on display screens in a manually changeable and adjustable manner. In such a wide television receiver, when the format or the type of an incoming television signal changes, complicated manual operation tends to be required to provide a desired manner of indication of every picture on a display screen.